I would say because it relies on an hardware key, which few of your users are going to have anyway. Any tech requiring an hardware component is going to be much slower to deploy.
I know there is still much interest in deploying it for internal/employee authentication in large organizations where you control the app login and the employee hardware. Some organizations that wrongly deployed multi factor auth based on SMS have realized that was a poor choice and are looking for alternatives.
> I would say because it relies on an hardware key
This isn’t true on Apple, Google, or Microsoft devices which have a trusted hardware store – I use my MBP’s Secure Enclave for 90% of my logins since it’s just a Touch ID check.
I know there is still much interest in deploying it for internal/employee authentication in large organizations where you control the app login and the employee hardware. Some organizations that wrongly deployed multi factor auth based on SMS have realized that was a poor choice and are looking for alternatives.